Method of making hydrogen dioxid.



' NITED STATES PATENT OFFICE.

PAUL LEON I'IULIN, OF CLAVAUX, PAR RIOUPEROUX, FRANCE.

METHOD OF MAKING HYDROGEN DIOXID.

SPECIFICATION forming part of Letters Patent No. 692,139, dated January28, 1902. Application filed July 9, 1901. SerialIIo. 67,582. (Npecimens.)

ments in the Preparation of Oxygenated Water, of which the following isa full, clear, and exact description.

My invention relates to a process for the preparation of oxygenatedwater on a com mer- IO cial scale by means of sodium dioxid.

Oxygenated water is a solution of hydrogen dioxid in pure water, (H O+nAq.) It generally contains from ten to fifteen volumes of activeoxygen, and it is requisite that it should I 5 neither contain alkaliesnor salts in solution in sensible proportion. In short, for most uses itshould consist of a solution of H 0 practically free from foreignelements. It is this condition more especially which has hitherto 2orestricted the'direct use of sodium dioxid for the preparation ofoxygenated water, as this substance leaves in the solution eithercaustic soda or a salt of soda, and such a preparation is uot suited forthe purpose for which it is to be used, as it does not possess thequalities and stability required of oxygenated Water.

The process hereinafter described has for its object the manufacture ofoxygenated wa- 3o ter upon a commercial scale by the direct employmentof sodium dioxid.

The process consists in dissolving, with the necessary precautions,sodium dioxid (M1 0 in a solution of hydrofluoric acid maintained at asufficiently low temperature, whereby oxygenated water and solublefiuorid of sodiumv are formed.

o This solution is then treated with a suitable proportion of aluminiumfluorid under such conditions as to enter into combination with thesodium fluorid. An insoluble double fluorid of aluminium and sodium orartificial 5 cryolite is thus formed, the salt of sodium which remainedin the solution of oxygenated water being eliminated in this compound,the precipitate being separated by filtration and oxygenated water beingobtained practically free from objectionable compounds.

. The known rules, precautions, and care in the preparation ofoxygenated water of various degrees of concentration are of course to beobserved in operating by this process.

The process may be carried out in various ways, and I will describe someof the modifications which may be adopted.

First. The solution of hydrofluoric acid previously prepared may alreadycontain aluminium fluorid in solution, which represents the acid termedhydrofluo-aluminic acid,

and it is then only necessary to add the sodium dioxid to this solutionwith the necessary precautions, the insoluble cryolite being then formedwithout other addition.

Second. To the solution may be addedtwice the quantity of hydrofluoricacid necessary for the saturation of the sodium dioxid in solution, asolution being thus obtained con tainingNaFl+HFl+H O +nH Q Aluminiumhydrate is then added, which becomes transformed into aluminium fluoridand insoluble cryolite. In this way the aluminium fiuorid is formed inthe solution itself instead of being prepared previously. This resultmay also be obtained by in the first place adding aluminium hydrate tothe neutral solution and then adding hydrofluoric acid, the aluminabeing transformed into aluminium fluorid on contact with the sodiumfiuorid, whereupon insoluble cryolite is formed.

Third. It will be evident thatit is not necessary to convert the wholeof the sodium fluorid into insoluble double fiuorid, the function of thealuminium fluorid in my process being to remove that which could not beeliminated by known means. The sodium fluorid in excess which cannot bedissolved may first be allowed to settle, and so extracted, the portionwhich remains in solution being afterward precipitated by the aluminiumfluorid. Furthermore, when hydrofluoric acid is added to theneutralsolution of oxygenated water and sodium fiuorid with a view to producealuminium fluorid. by the addition of aluminium hydrate, theprecipitation of fresh quantities of sodium fiuorid is brought about,especially if the temperature be reduced at the same time. p

It will be understood that in all these modifications the acid ormaterials necessary may be added in several stages, that the reac* tionsmay be repeated or Varied in their order, and that successivesaturations with intermediate precipitations and filtrations may beeffected, and so on. Other more or less practical modifications may alsobemade as, for example, the sodium dioxid and the aluminium fluorid orthe alumina may be mixed and this mixture be immersed in thehydrofluoric-acid solution. The sodium dioxid may also be dissolved in asolution of aluminium fluorid, producing a mixed precipitate of doublefluorid and alumina, due. The common aluminium fluorid as it is obtainedby saturating hydrofluoric acid with aluminium is insoluble in water;but an aqueous solution of aluminium fluorid may be prepared by themethod of St. Claire-Devillethat is, by attacking thealuminium or kaolinby hydrofluosilicic acid. Byusing an excess of the aluminium orkaolinthe reaction gives a precipitate of silica producedby the decompositionof the silicium fluorid, and it leaves a solution of aluminium fiuorid.According to the opinion of St. Olaire-Deville the soluble alu miniu mfluorid produced under such conditions will be a hydrated variety, (AlFl 7H O.) It is sometimes preferable in practice in order to facilitatethe operation and avoid trouble to sacrifice the purity of the insolubledouble fiuorid and to admit an excess of aluminium fiuorid or of aluminaor of some insoluble compounds hereinafter mentioned.

By combining in various manners the stages and modifications ofmyprocess I may vary to a certain degree the nature or the proportions ofthe utilized agents or of the fluorated by-products. Thus when I want toobtain the minimum of cryolite I preferably proceed as-follows: Isaturate in one or more operations the solution of hydrofluoric acidwith sodium dioxid by stirring and maintaining at a low temperature,separate the excess of sodium fluorid which naturally deposits, and addhydrofluoric acid in such a quantity asto have atleast and as exactly aspossible one molecule of hydrofluoric acid for one molecule of alkalinefluorid remaining in solution.

The addition of the acid generally gives a precipitation of sodiumfluorid in .the form of granular crystals, mostly composedoffluorid-hydrosulfate, separate this new precipitate and obtain asolution of oxygenated water containing not more than twenty totwenty-five grams of-NaFl per liter,withthe hydrofluoric acid in excess,(molecule of HF1 to molecule of'NaFl.) I. then add gelatinous alumina-inorder to saturate the whole of the acid and form the precipitate ofcryolite,

leave in the solution the whole or part of the precipitates of sodiumfluorid which have been obtained successively before the action of thealuminium fluorid, and I stir when the latter begins to act.

The process which has just been exposed remains the sameif I add firstalumina in excess to the neutral solution of alkaline fiuorid and if Ithen add, gradually and by stirring, a corresponding quantity ofhydrofluoric acid. In such case there is advantage to secure thecomplete conversion of the alumina by means of a moderate excess ofhydrofluoric acid, which is then saturated on its turn by an excess ofgelatinous alumina. I also vary the use of hydrofluo-aluminic acid(Al,F1 .6HFl) by adding such compound to the solution of oxygenatedwater and ofsodium "fluorid in such a quantity that the whole of thefluor contained therein will be at least. equal tothe fluor of thesodium fluorid contained in the oxygenated solution. I then saturatethehydrofluoric acid with gelatinous alumina, as before, and I alsorender-insoluble the sodium fluorid in the form of artificialcryolite.

The hereinbefore-described operations are sometimes followed byatreatment'with barytain aqueous solution or lime-water Which is added atwill and according to circumstances in order to elminate any sulfuricacid which the gelatinous alumina may contain and to destroy inthe formof insoluble residues the reagents which may be in excess and insolution.

When it is not desired to elmi'natethe Whole of the sodium saltcontainedin the oxygen ated solution, I may after having separated as much aspossible of the sodium fiuorid treat-With asoluble salt ofaluminium,such as the chlorid, sulfate, or fiuosilicate, ds'c. The fluoris thus elminated, and a fresh quantity of sodic salt is renderedinsoluble and then separated. There then remains in the solutiona-little sulfate or chlorid or fiuosilicate of sodium. That whichremains of the latter after filtration may be converted into chlorid bythe addition of barium chlorid, so as to form less soluble bariumfluosilicatewhich is separated.

It is evident that the details of operation and the means enabling toput my process into practice are too numerous-to be all described. Theprinciples and the examples I have exposed enable ineach particular caseto apply my process in order to obtain an a-iccessory result.

1. The process herein described of produc ing an aqueous solution ofhydrogen dioxid, which consists in decomposing sodium dloxid byhydrofluoric acid in the presence of Water to form hydrogen dioxid, andconverting the sodium into an insoluble precipitate of cryolite byaluminium fiuorid, as set forth.

2. The process herein described of producing an aqueous solution ofhydrogen dioxid, which consists in decomposing sodiumdioxid with anexcess of hydrofluoric acid, then addcipitate, and finally adding analkaline earth,

ing aluminium hydrate thereby forming aluminium fluorid in quantitiessulficient to combine with the sodium fluorid to completely precipitateit as cryolite, substantially as described.

3. The process herein described of producing an aqueous solution ofhydrogen dioxid, which consists in decomposing sodium dioxid byhydrofluoric acid in the presence of water, converting the sodium intoan insoluble presuch as baryta or lime, to render insoluble the reagentsthat may be in excess as set forth.

The foregoing specification of my improve- I 5 ments in the preparationof oxygenated water signed by me this 21st day of June, 1901.

PAUL LEON HULIN.

Witnesses:

RIeIo J 0Y0, Fils, RALPH CLEWELL SUPER,

